Some aspects of the osmotic lysis of erythrocytes. I. A reexamination of the osmotic lysis method

Haemolysis of human and sheep red blood cells in glycerol media: the effect of pH and the role of band 3

Haemolysis of red blood cells (RBC) in glycerol media may be measured spectrophotometrically. The haemolytic process in a rapid phase obeys a first order rate law. The rate constant expresses the rate of haemolysis. To gain a better understanding of the mechanism of haemolysis in glycerol media, the effects of pH and band 3 inhibitors on the rate of haemolysis in human and sheep RBC were observed. Over the pH range used (pH 5.8-10.0), the rate of haemolysis decreased with increase in pH in sheep RBC. By contrast, the rate of haemolysis increased from pH 5.8 to 6.4 and decreased above pH 6.4 in human RBC. The different effects of pH on the rate of haemolysis are due to inhibition of glycerol permeability by H(+) in human RBC but not in sheep RBC. This is supported by the different effects of temperature and Cu(2+) on the rate of haemolysis in human and sheep RBC. We did not observe complete inhibition of haemolysis by the classical band 3 inhibitor, 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Another band 3 inhibitor 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS) showed only weak inhibition. Phenylgloxal (PG), another band 3 inhibitor, had no effect whatsoever on the rate of haemolysis. These results indicate that the anion pathway of band 3 is not the preferred route of transport of glycerol in mammalian RBC.

Biocompatibility and enzymatic degradation studies on sulphated hyaluronic acid derivatives

The biocompatibility and susceptibility to enzymatic degradation of new heparin-like polysaccharides obtained by hyaluronic acid sulphation (HyalSx) were evaluated. In particular, HyalSx cytotoxicity and cytocompatibility were assessed by the direct contact method using fibroblasts L929 and human endothelial cells. The results showed that hyaluronic acid derivatives are devoid of any cytotoxic effects on mouse fibroblasts and they are cytocompatible. The haemolysis test showed that the sulphated polysaccharides are not haemolytic. HyalSx susceptibility to enzymatic degradation was tested in the presence of both hyaluronidase and chondroitinase ABC. It was demonstrated that the introduction of sulphate groups along the hyaluronic acid chain makes the macromolecules resistant to enzymatic digestion.

Trypanosoma brucei: a quick method for separating blood-stream trypomastigotes from infected blood by differential osmotic lysis

1. The degree of rat erythrocyte lysis and immobilization of Trypanosoma brucei in infected blood by buffered hypotonic solutions of sodium chloride and sources was studied. 2. At 0.3% sodium chloride solution 98% hemolysis of erythrocytes was achieved while 95% of the original bloodstream trypomastigotes survived and were found to be motile and viable for biochemical study. 3. Further increase in the concentration of sodium chloride above 0.3% revealed an increase in the immobilization of trypanosomes and a decrease in the erythrocyte hemolysis. 4. Bloodstream trypomastigotes have been prepared by differential osmotic lysis of infected blood in 0.3% sodium chloride solution and used for studying their metabolism.

Slow phase hemolysis in hypotonic electrolyte solutions

When a population of erythrocytes is partially hemolyzed the time course of hemolysis can be divided into a fast phase and a slow phase. The slow phase occurs with both rapid and gradual addition of the hypotonic medium (rapid and gradual hemolysis). There is no difference in the osmotic fragility of erythrocytes remaining at 60 minutes after rapid or gradual hemolysis. Erythrocytes near their critical hemolytic volume have an equimolar ouabaininsensitive sodium-potassium exchange. Critical non-hemolytic swelling with resulting stress on the membrane appears requisite to slow phase hemolysis since more non-penetrant sucrose is required to prevent slow phase lysis rather than that which would be predicted from the intracellular colloid osmotic pressure due to hemoglobin. Sucrose protection from slow phase hemolysis thus depends not only on counter-balancing the colloid osmotic pressure, but also removal of sufficient intracellular water to prevent critical membrane strain. This model is consistent with that proposed by Katchalsky. Irreversible membrane changes associated with hypotonic stress manifested by persistent stomatocytic shape change and membrane wrinkling on return of cells to isotonicity appear to be due to critical changes in membrane components. Such cells, having normal indices and specific gravity are less deformable than control cells in 2.8 mum pore size polycarbonate filters.